Since Marbury v Madison the Court has become the final arbiter of ‘constitutionality’.
A majority of Justices inimical to rights could easily rule that any gun ban, e.g. Feinstein’s “Mr & Mrs America turn them all in” is constitutional if such a law was ever passed.
(and Dianne files such a law every new congressional term)
You’d wind up with a de facto repeal. We’re not stupid.